Seat tube assembly for a bicycle or the like

ABSTRACT

A bicycle seat tube assembly includes an arced component, a bottom bracket positioned below the arced component, and a seat tube including a pivot attachment at a lower end of the seat tube. The arced component includes a lower curved surface with a plurality of holes. The pivot attachment is coupled to the bottom bracket so that the arced component is pivotable relative to the seat tube about the bottom bracket, resulting in multiple seat tube positions between a fully forward position and a fully back position. A locking mechanism is configured to selectively lock the seat tube to the arced component. The locking mechanism includes a lock ring with a plurality of lock pins and a spring that pushes the lock ring towards the arced component. The lock ring and the spring surround the seat tube The lock ring is movable between a locked position and an unlocked position.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application claims priority from U.S. Provisional Application No.61/687,926, filed Apr. 30, 2012, which is incorporated herein byreference in its entirety. This application claims priority from U.S.Provisional Application No. 61/743,635, filed Sep. 6, 2012, which isincorporated herein by reference in its entirety. This applicationclaims priority from U.S. Provisional Application No. 61/851,061, filedMar. 1, 2013, which is incorporated herein by reference in its entirety.This application claims priority from U.S. Provisional Application No.61/791,585, filed Mar. 15, 2013, which is incorporated herein byreference in its entirety.

BACKGROUND

The present invention relates generally to the field of seat assembliesand frames for bicycles and the like.

SUMMARY

One embodiment relates to a bicycle seat tube assembly including anarced component, a bottom bracket positioned below the arced component,and a seat tube including a pivot attachment at a lower end of the seattube. The arced component includes a lower curved surface with aplurality of holes. The pivot attachment is coupled to the bottombracket so that the arced component is pivotable relative to the seattube about the bottom bracket, resulting in multiple seat tube positionsbetween a fully forward position and a fully back position. A lockingmechanism is configured to selectively lock the seat tube to the arcedcomponent at one of the seat tube positions. The locking mechanismincludes a lock ring with a plurality of lock pins and a spring thatpushes the lock ring towards the arced component. The lock ring and thespring surround the seat tube The lock ring is movable between a lockedposition in which the lock pins are inserted into the holes and anunlocked position in which the lock pins are removed from the holes andthe arced component is free to pivot about the bottom bracket.

Another embodiment relates to a bicycle frame including a head tubeconfigured to receive a handlebar, a bottom bracket, a down tubeextending rearward and downward from the head tube to the bottombracket, a top tube extending rearward form the head tube, an arcedcomponent including a forward end coupled to the top tube and a lowercurved surface with a plurality of holes, and a seat tube including apivot attachment at a lower end of the seat tube. The pivot attachmentis coupled to the bottom bracket so that the arced component ispivotable relative to the seat tube about the bottom bracket, resultingin multiple seat tube positions between a fully forward position and afully back position. A locking mechanism is configured to selectivelylock the seat tube to the arced component at one of the seat tubepositions. The locking mechanism includes a lock ring with a pluralityof lock pins and a first spring that pushes the lock ring towards thearced component. The lock ring and the first spring surround the seattube The lock ring is movable between a locked position in which thelock pins are inserted into the holes and an unlocked position in whichthe lock pins are removed from the holes and the arced component is freeto pivot about the bottom bracket. A second spring is coupled betweenthe head tube and the seat tube to pull the seat tube towards the fullyforward position. The second spring is located within the top tube.

Another embodiment relates to a bicycle including a frame including ahead tube, a top tube extending rearward from the head tube, an arcedcomponent having a forward end coupled to the top tube and a lowercurved surface with a plurality of holes, and a bottom bracketpositioned below the arced component and a seat tube including a pivotattachment at a lower end of the seat tube. The pivot attachment iscoupled to the bottom bracket so that the frame is pivotable relative tothe seat tube about the bottom bracket, resulting in multiple seat tubepositions between a fully forward position and a fully back position. Alocking mechanism is configured to selectively lock the seat tube to thearced component at one of the seat tube positions. The locking mechanismincludes a lock ring with a plurality of lock pins and a first springthat pushes the lock ring towards the arced component. The lock ring andthe first spring surround the seat tube The lock ring is movable betweena locked position in which the lock pins are inserted into the holes andan unlocked position in which the lock pins are removed from the holesand the frame is free to pivot about the bottom bracket. A second springis coupled between the head tube and the seat tube to pull the seat tubetowards the fully forward position. The second spring is located withinthe top tube. A saddle is movably coupled to the seat tube so that thesaddle is adjustable up and down relative to the seat tube. A frontwheel is coupled to the frame, a rear wheel is coupled to the frame, anda handlebar is coupled to the head tube. With the lock ring in theunlocked position, the seat tube remains stationary and the frame pivotsto follow the terrain on which the bicycle is being ridden

Other embodiments relate to a bicycle frame where the seat tube assemblyremains in a fixed position with respect gravity and the riders' mostefficient body position and the remainder of the frame assembly isallowed to rotate about the bottom bracket. In some embodiments, theframe includes an arced component that is designed so that it guides theseat tube assembly within its range and provides a radiused surface tomount removable insert strips. In some embodiments, insert strips aredesigned using non concentric radii so that one arc design can be usedfor any size bicycle frame. The insert strips may have slottedpositioning pockets that accept stepped and tapered locking pins andallow the pins to be misaligned in frame assembly without compromisingthe stability of the locking mechanism. The insert strips may have aninside wall that can be precision fitted to the seat tube flatsmaintaining a slip fit required for accurate and sustained locking ofthe frame/seat tube relation. The seat tube assembly may be integratedwith a remotely controlled hydraulic seat post assembly that allows therider to raise and lower the saddle independently or in conjunction withthe rotation of the frame. In some embodiments, the frame assembly usesan extension spring or optional hydraulic assembly to pull the frametowards the fixed seat tube assembly when the rider chooses to adapt theframe geometry for any terrain conditions they encounter (e.g. up ordown hill) or to benefit the rider's bio mechanical position.

Other embodiments relate to a fixed seat tube assembly and lockingmechanism that provides a way for the saddle to remain fixed while therest of the frame and associated wheels, etc to follow the terrain thusallowing the rider to maintain their maximum power position by virtue ofnot moving with respect to gravity and their predetermined powerposition.

Other embodiments relate to a fixed seat tube assembly and lockingmechanism that allows a rider to fine tune their riding position bypulling or pushing the frame toward or away from the fixed seat tubeassembly. In some embodiments, a cable or hydraulic assembly allows therider to disengage the frame from the seat tube assembly as the riderdetermines using a control typically mounted on the handlebars. Thecable assembly may include a mechanical advantage design that lessensthe required on the thumb lever. A lock ring may be disengaged andengaged by the cable assembly in a symmetrical and even force based onthe cable pulley system. A coaxial mounted extension spring may behoused inside the top tube and damped by a tube liner that pulls theframe toward the fixed seat tube or allows the frame to move freely foreand aft of the fixed seat tube as desired without the need of the riderto push or pull in order to change the frame/seat tube relationship. Insome embodiments, a frame design made up of “V” shaped tubes extendingfrom each end of the arc to the bottom bracket to form a solid structuremaintains the integrity of the locking mechanisms. In some embodiments,an eccentric bushing where the rear axle passes allows for the preciserear wheel alignment to the arc leading to a shorter overall wheelbase.In some embodiments, a spring steel or hard bearing material lowerbottom bracket strap holds the seat tube assembly against the bottombracket while allowing a smooth pivot point for the frame to rotate withrespect to the fixed seat tube. A second spring steel or hard bearingmaterial may be sandwiched between the bottom bracket and the seat tubeassemblies' lower yoke providing a hard running surface between thetypically softer frame materials. A shock absorbing and height adjustingassembly may be used, allowing for precision adjusting of the head tubeangle and shock relief of the front section of a frame. In someembodiments, a spring retainer ring allows for the tension adjusting ofthe compression spring that pushes the locking ring with it's pins upinto the insert strips. Locking pins designed with a taper as well as astep may be used to allow for fast and accurate insertion in and out oftheir slotted receptacle pockets. As the pins seat their tapered lowersection is forced to wedge into the insert strips creating a solid fitthat mimics the weld used on a traditional bike

Another embodiment relates to a method for riding or racing a bicyclethat uses physics and adaptable frame geometry design to provide a wayfor a rider to maintain their most powerful and/or most comfortableposition by allowing the seat tube assembly to remain fixed with respectto gravity and a riders' leg/body position while the remaining framegeometry is allowed to pivot about the bottom bracket at the directionof the rider thus adapting to various terrain conditions e.g. up or downhill. If it has been determined that a rider's most efficient powerposition with respect to the frame geometry on flat ground then changingthe terrain would not alter that ultimate position. Because atraditional bicycle frame is “fixed” it stands to reason that the mostefficient position is diminished when any terrain other than flat isencountered. The method described here allows for the rider to maintainthat most efficient position by keeping the seat tube fixed with respectto gravity and the riders' body position while encountering variableterrain.

Alternative exemplary embodiments relate to other features andcombinations of features as may be generally recited in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become more fully understood from the followingdetailed description, taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a perspective view of a bicycle according to an exemplaryembodiment;

FIG. 2 is a perspective view of a bicycle according to an exemplaryembodiment;

FIG. 3 is a perspective view of the bicycle of FIG. 2 on flat ground;

FIG. 4 is a perspective of the bicycle of FIG. 2 going up a moderatehill;

FIG. 5 is a perspective of the bicycle of FIG. 2 going up a steep hill;

FIG. 6 is a perspective of the bicycle of FIG. 2 going down a steephill;

FIG. 7 is an exploded view of a bicycle frame according to an exemplaryembodiment;

FIG. 8 is an exploded view of a bicycle frame according to an exemplaryembodiment;

FIG. 9 is an exploded view of a bicycle frame according to an exemplaryembodiment;

FIG. 10 is a perspective view of a portion of a bicycle frame, with somecomponents omitted for clarity;

FIG. 11 is an exploded view of an arced component of a bicycle frameaccording to an exemplary embodiment;

FIG. 12 is a bottom perspective view of an arced component of a bicycleframe according to an exemplary embodiment;

FIG. 13 is a perspective view of a portion of a bicycle frame accordingto an exemplary embodiment;

FIG. 14 is a perspective view of a portion of the bicycle frame of FIG.13;

FIG. 15 is a perspective view of a portion of the bicycle frame of FIG.13;

FIG. 16 is a perspective view of a portion of the bicycle frame of FIG.13, with some components omitted for clarity;

FIG. 17 is a perspective view of a portion of the bicycle frame of FIG.13, with some components omitted for clarity;

FIG. 18 is an exploded view of a portion of the bicycle frame of FIG.13; and

FIG. 19 is a perspective view of a portion of a bicycle according to anexemplary embodiment.

DETAILED DESCRIPTION

Before turning to the figures, which illustrate the exemplaryembodiments in detail, it should be understood that the application isnot limited to the details or methodology set forth in the descriptionor illustrated in the figures. It should also be understood that theterminology is for the purpose of description only and should not beregarded as limiting.

As shown in the Figures, a bicycle frame 100 as described hereinaddresses the problem that all riders have when they encounter changingterrains while riding. The typical bike frame is primarily designed tobe used most efficiently on flat terrain. Even if a frame is customfitted to a specific rider it is done based on flat ground. The factthat a seat tube on industry standard frames is fixed at a particularangle (typically between 70 and 74 degrees) is an admission that it isan “average” of all terrains that it will encounter. The bicycle frame100 provides a seat tube 105 that can be indexed on the fly at varyingangles depending on the riders' requirements. This means that a ridercan quickly move and lock (index) the seat tube 105 to a position thatprovides them with the greatest efficiency at that moment during theride. This is due to the fact that there is one physical position forany given rider that produces the greatest power to the cranks 110 andthat position changes as the terrain changes.

An exemplary embodiment of a bicycle 115 including the frame 100 isillustrated in FIGS. 1-2. As shown in FIG. 2, the frame 100 includes ahead tube 245, a top tube 215, a down tube 275, the seat tube 105, abottom bracket 140, an arced component 180, four support struts 230, aseat stay 117, and a chain stay 119. A front wheel 121 is supported by asuspension fork 123. The front wheel is braked by a disc brake 127. Thehandlebars 310 include a stem 129. A drop out 131 allows a rear wheel133 to be removed from the frame 100. The seat 135 is supported by aseat post 137 and secured by a seat post clamp 139.

The method that allows the rider to change the riding position is builtinto the design of the frame 100. This method must be practical and safefor it to become a realistic standard in the bicycle industry. Thefollowing steps are used to provide the “method” that the frame 100 andbicycle 115 use to obtain maximum efficiency. The rider traveling on aroad or trail uses a thumb lever 120 to release a locking mechanism 125that holds the pivoting seat tube 105 in place (step 1). The seat tube105 is spring loaded forward by a spring 130 so that it is easilypositioned by the rider even when moving uphill (step 2). As the riderencounters a particular terrain, he or she unlocks and positions theseat tube 105 to the position that they determine to be the mostefficient or comfortable (step 3). When the thumb lever 120 is releasedthe locking mechanism 125 latches to secure the seat tube 105 (step 4).The ability of the rider to quickly and positively position themselvesat their most efficient or comfortable location provides the method formaximum riding performance.

For reference, FIGS. 5-6 show the positions of the frame 100 withrespect to the fixed seat tube 105 at the limits of its range. FIG. 3shows the frame 100 with the bicycle 115 on flat ground and the seattube 105 at a mid range position. FIG. 4 shows the frame 100 with thebicycle going up a moderate hill and the seat tube 105 at a partiallyforward position. FIG. 5 shows the frame 100 with the bicycle 115 goingup a steep hill and the seat tube 105 at a fully forward position. FIG.6 shows the frame 100 with the bicycle 115 going down a steep hill andthe seat tube 105 at a fully back position. Note that the seat 135 andseat tube 105 remain fixed while the frame 100 pivots about the bottombracket 140 compensating for the change in terrain.

Various exemplary embodiments of the frame 100 are shown in explodedviews in FIGS. 7-9. The bicycle frame 100 (mountain, city, road,triathlon, beach, etc) includes an integrated seat tube assembly 145based on the ability for the seat tube assembly 145 to index into thebest and/or most efficient position as determined by the rider duringoperation. The seat tube 105 is released, indexed, and locked into placeby an assembly and mechanism 125 designed specifically to hold solid theassembly 145 while riding the bicycle 115. The locking mechanism 125 isdesigned to “wedge” into place so that a locking ring 155 and pins 160(shown in FIG. 10) do not slip or move during the bicycle's operation.The locking mechanism 125 is operated via a cable release lever 120conveniently located to the rider. The seat tube assemblies' lowerconnection 165 pivots around the centerline axis of the bottom bracket140 so that the height of the seat 135 does not change during or afterthe indexing operation is performed. The upper bottom bracket clamp half170 is held in place with a spring steel lower clamp 175 that allows forthe smooth indexing of the seat tube 105. As shown in FIG. 9, a remotelycontrolled hydraulic seat post assembly 177 allows the rider to raiseand lower the saddle 135 independently or in conjunction with therotation of the frame 100. An eccentric bushing 179, where the rear axlepasses, allows for the precise rear wheel alignment to the arc 180,leading to a shorter overall wheelbase.

As shown in FIGS. 11-14, the bicycle frame 100 includes an arcedcomponent 180 that furnishes the seat tube locking pins 160 a matchingradius for the latching. A spring 185 is slid onto a ring 190 andclamped in place along the seat tube 105 and pushes the locking ring 155and pins 160 upward engaging holes 195 in the underside of the arc, thusholding the seat tube assembly in place until released again by therider to another position along the arc 180. The seat tube 105 can indexinto holes 195 laid out along the underside of the arc 180 approximatelyevery 2 degrees for the length of the arc 180. Tapered locking pins 160are used so that when the lock ring 155 is pushed into the mating holes195 in the bottom of the insert strips 200, the lower taper of the pins160 will wedge into the holes 195 creating a solid hold so that the seattube 105 does not wiggle when the bike 115 is ridden.

Different bicycle styles (e.g. mountain, road) may use arcs 180 ofdifferent lengths and radii depending on the design criteria of theparticular frame. The underside of the arc 180 may include an insert 200of a harder material for the locking pins 160 to increase the life ofthe locking mechanism 125. A pull force reducing pulley mechanism 205(including cables 207 and 209) is used to lessen the force necessary torelease the pins 160 from the arc 180. The cable or hydraulic releasemechanism 300 is designed so that there is equal and symmetrical pull onthe lock ring 155 to insure positive locking of the pins 160. Slideinserts may be used on some models inside the arc's surfaces to lessenthe friction between the seat tube 105 and the arc 180. When releasedthe seat tube 105 is pulled toward the front of the bicycle using aspring and cable assembly 210 located inside a top tube 215 of the frame100. The frame 100 may be made using a variety of state of the artmaterials, and the design is not dependant on any single material. Theframe 100 accepts additional industry standard bicycle componentstypically used to make up the completed bicycle 115.

FIGS. 11 and 12 illustrate the arc 180. The arc body 181 is formed oftwo halves 183 and 187. The halves 183 and 187 are pinned and boltedtogether. The halves 183 and 187 can be cast with better precision. Thearc 180 defines a tube guide slot 189. The radius plate modules orinserts 200 are made from a hard material like titanium or siliconcarbide, eliminating the need for pressed in steel strips. The bottomradius 191 of the insert 200 is changed for different bike sizes. Theradius 191 determines the size of the bike (e.g., a 16″ radius resultsin a 16″ bike). The top radius 193 of the insert 200 matches the innerradius of the arc body 181. The inserts 200 are removable. The arc body181 is the same for all bikes (e.g., for all mountain bike sizes)because the inserts 200 are matched to the bike size. Locking holes 195,slots, or teeth are formed in the insert 200. The inserts 200 alsoinclude mounting holes 197 and registration slots 199.

One of the main components of all of the bikes is the arced component180 at the top of the indexing seat tube assembly and mechanism. The arc180 may be made in modular sections that allow for easier manufacturingand design flexibility. The arced section 180 is used as a guide for theseat tube 105 and maintains a tight fit of all the locking components.The lower module 200 that contains the radius where the locking ring 155attaches may be made so that it can be replaced if damaged without theneed to replace the entire arc 180. This module 200 may be made of astronger material such as steel, titanium, or silicon carbide thateliminates the need for a pressed in insert into the bottom of the arc180 for rigidity of the locking mechanism 125. The radius plates 200 arefurther used to allow one arc size to fit all bike sizes with only theneed to use the correct radius plate 200 to match the size bike beingbuilt. The radius plates 200 contain the index holes 195 or teeth thataccept the pins 160 or teeth of the lock ring 155. If the radius plates200 are damaged or worn only they need to be replaced instead of theentire arc 180.

A removable insert strip 200 that attaches to the underside of the arc180 allows for the arc 180 to be the same for all size bikes. Thedifferent size insert strips 200 have a top radius that is always thesame and match the bottom radius of the arc 180 but a lower radius thatvaries depending on the size bike it is being used with. Because thevarious bike sizes require that the final bottom radius of the arc'sinsert strip 200 where the lock mechanism 125 slides is a set distancefrom the middle of the bottom bracket 140 (e.g. 17″ radius for a 17″frame), it is efficient to have a design where the same arc body 181 canbe used for all bikes. The range of the seat tube movement within thearc 180 may be controlled with stops or the dimensions of the arc 180.

As shown in FIG. 13, the seat tube 105 uses machined flats 220 about thetube 105 that keep the locking ring 155 from rotating or twisting duringoperation. A visco-elastic shock dampening material or pad 225 ismounted in a location between the spring loaded seat tube assemblieslocking mechanism 125 and a forward arc structure 230 to protect theuser or any person from potential injury. The lock pins 160 may beslightly offset so that they are forced into a wedging connection intothe arc's lower mating holes 195. This will hold the locking mechanism125 in a much tighter bond. The clamp 190 is used to adjust the tensionof the push up spring 185. The V shaped support struts 230 add rigidityto the entire frame 100 as well as support and stability to the arc 180.As shown in FIG. 15, a bracket 235 that accommodates a bicycle industrystandard front derailleur 240 is mounted between the right side Vsupports 230 in a way that allows for the seat tube 105 to move freely.If a front derailleur 240 is required, it is designed with an open lowercage 320 that allows the chain 325 to move without contact. Thisderailleur design also allows for its removal from the frame 100 withoutthe need to separate the chain 325.

As shown in FIG. 9, a threaded insert 150 located at the bottom of ahead tube 245 that allows fine tuning of the head tube length for properfit of the fork 250 into the head tube 245. This insert 150 can also beused to change the angle of the head tube 245 with respect to levelground. A shock absorbing cartridge may be integrated into the head tubeadjustment ring 150 of road or triathlon bike frames to control fatigueof the front sections of the frame 100 as well as the rider's upperbody.

As shown in FIG. 16, the seat pull spring assembly 210 is mountedcoaxial with the top tube 215 so that it can be pulled back and forth asrequired. The assembly 210 is anchored (e.g., by a flat head bolt 255)to the head tube 245 for maximum stability. The assembly 210 is coveredwith a plastic or rubber material tube liner 260 to lessen noise duringuse. The assembly 210 is anchored to the seat tube 105 via a quickrelease wire or cable 265 around the circumference of the seat tube 105.The quick release wire 265 forms a wire loop 267 and cable stop 269. Thequick release wire 265 is coupled to the seat tube pull spring 130

As shown in FIG. 17, a down tube yolk 270 is used to attach the downtube 275 to the bottom bracket 140 in a way that allows for clearancefor the seat tube 105 to arc forward without obstruction. The seat tubepivot attachment 165 is attached to the bottom bracket 140 using aspring steel band 175 that allows for a smooth rotation of the seat tubeassembly around the bottom bracket 140. The surfaces of the rotatingparts can be easily lubricated through the opening at the top of theseat tube 105. A hardened steel, copper, or other bearing material 315is used around the diameter of the bottom bracket 140 so that the lowerclamping bracket 175 rides on a hardened surface acting as a bearing toprevent wear and noise.

The road bikes (that includes the triathlon bike) use a cable seatrelease 290 (as shown in FIG. 19) instead of the thumb release 120 usedon mountain bikes (e.g., as shown in FIGS. 1-2). The seat release cable290 is an extension of the main cable 300 and spans between the curvedsections 305 of the handlebars 310 with stops at the required positions.As shown in FIG. 19, for a bike with a road style drop handlebar 310,the lock ring release mechanism can be actuated using an extension 290of the pull cable 300 that spans between two sections 305 of the bar310.

Integrated into the seat tube assembly 145 is a hydraulic drop seatassembly 330 that may be used independently or simultaneously with thepivoting seat tube 105 to raise or lower the seat 335 as desired by therider.

Because the bike frame 100 and seat tube assembly 145 are separate, theseat tube assembly 145 can maintain a fixed position with respect togravity and the riders' body position while the rest of the frame 100pivots at the bottom bracket 140 when desired. Because the seat tubeassembly 145 can remain stationary while the remainder of the bike 115follows the terrain, the rider maintains their maximum power position.

The construction and arrangement of the elements of the apparatus asshown in the exemplary embodiments are illustrative only. Although onlya few embodiments of the present disclosure have been described indetail, those skilled in the art who review this disclosure will readilyappreciate that many modifications are possible (e.g., variations insizes, dimensions, structures, shapes and proportions of the variouselements, values of parameters, mounting arrangements, use of materials,colors, orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter recited. For example,elements shown as integrally formed may be constructed of multiple partsor elements. The elements and assemblies may be constructed from any ofa wide variety of materials that provide sufficient strength ordurability, in any of a wide variety of colors, textures, andcombinations. Additionally, in the subject description, any use of theword “exemplary” is used to mean serving as an example, instance, orillustration. Any embodiment or design described herein as “exemplary”is not necessarily to be construed as preferred or advantageous overother embodiments or designs. Rather, use of the word “exemplary” isintended to present concepts in a concrete manner. Accordingly, all suchmodifications are intended to be included within the scope of thepresent disclosure. Other substitutions, modifications, changes, andomissions may be made in the design, operating conditions, andarrangement of the preferred and other exemplary embodiments withoutdeparting from the scope of the appended claims.

The order or sequence of any process or method steps may be varied orre-sequenced according to alternative embodiments. Anymeans-plus-function clause is intended to cover the structures describedherein as performing the recited function and not only structuralequivalents but also equivalent structures. Other substitutions,modifications, changes and omissions may be made in the design,operating configuration, and arrangement of the preferred and otherexemplary embodiments without departing from the scope of the appendedclaims.

What is claimed is:
 1. A bicycle seat tube assembly, comprising: an arced component including a lower curved surface having a plurality of holes therein; a bottom bracket positioned below the arced component; a seat tube including a pivot attachment at a lower end of the seat tube, wherein the pivot attachment is coupled to the bottom bracket so that the arced component is pivotable relative to the seat tube about the bottom bracket, resulting in a plurality of seat tube positions between a fully forward position and a fully back position; and a locking mechanism configured to selectively lock the seat tube to the arced component at one of the seat tube positions, wherein the locking mechanism includes a lock ring with a plurality of lock pins and a spring that pushes the lock ring towards the arced component, wherein the lock ring and the spring surround the seat tube, and wherein the lock ring is movable between a locked position, in which the lock pins are inserted into the holes, and an unlocked position, in which the lock pins are removed from the holes and the arced component is free to pivot about the bottom bracket.
 2. The bicycle seat tube assembly of claim 1, wherein the spring is secured to the seat tube by a clamp and the clamp is movable relative to the seat tube to adjust the tension of the spring.
 3. The bicycle seat tube assembly of claim 1, wherein the seat tube includes a plurality of flats that prevent the lock ring from rotating relative to the seat tube.
 4. The bicycle seat tube assembly of claim 1, further comprising: a lock ring release mechanism coupled to the locking mechanism for unlocking the lock ring, wherein the lock ring release mechanism is configured to provide an equal and symmetrical pull on the lock ring when moving the lock ring to the unlocked position.
 5. The bicycle seat tube assembly of claim 4, wherein the lock ring release mechanism is coupled to the locking mechanism by at least one cable.
 6. The bicycle seat tube assembly of claim 5, further comprising a pulley mechanism coupled between the cable and the lock ring.
 7. The bicycle seat tube assembly of claim 4, wherein the lock ring release mechanism is hydraulically coupled to the locking mechanism.
 8. The bicycle seat tube assembly of claim 1, further comprising: a first support strut extending from the bottom bracket to a first end of the arced component; and a second support strut extending from the bottom bracket to a second end of the arced component.
 9. The bicycle seat tube assembly of claim 1, wherein the arced component includes a removable insert strip that forms the lower curved surface.
 10. The bicycle seat tube assembly of claim 9, wherein the removable insert strip includes an upper curved surface that has a radius different than the radius of the lower curved surface of the removable insert strip.
 11. The bicycle seat tube assembly of claim 10, wherein the arced component further includes an arc body that receives the removable insert strip, the arc body including an arc body lower curved surface having a radius equal to the radius of the upper curved surface of the removable insert strip.
 12. The bicycle seat tube assembly of claim 9, wherein the locking pins are tapered, and wherein with the lock ring in the locked position, the tapered lock pins are wedged into holes of the removable insert strip.
 13. The bicycle seat tube assembly of claim 1, further comprising: a saddle movably coupled to the seat tube so that the saddle is adjustable up and down relative to the seat tube; and a hydraulic seat post assembly for raising and lowering the saddle.
 14. A bicycle frame, comprising: a head tube configured to receive a handlebar; a bottom bracket; a down tube extending rearward and downward from the head tube to the bottom bracket; a top tube extending rearward form the head tube; an arced component including a forward end coupled to the top tube and a lower curved surface having a plurality of holes therein; a seat tube including a pivot attachment at a lower end of the seat tube, wherein the pivot attachment is coupled to the bottom bracket so that the arced component is pivotable relative to the seat tube about the bottom bracket, resulting in a plurality of seat tube positions between a fully forward position and a fully back position; a locking mechanism configured to selectively lock the seat tube to the arced component at one of the seat tube positions, wherein the locking mechanism includes a lock ring with a plurality of lock pins and a first spring that pushes the lock ring towards the arced component, wherein the lock ring and the first spring surround the seat tube, and wherein the lock ring is movable between a locked position, in which the lock pins are inserted into the holes, and an unlocked position, in which the lock pins are removed from the holes and the arced component is free to pivot about the bottom bracket; and a second spring coupled between the head tube and the seat tube to pull the seat tube towards the fully forward position, wherein the second spring is located within the top tube.
 15. The bicycle frame of claim 14, further comprising: a cable that couples the second spring to the seat tube; and a tube liner located within the top tube to damp the second spring and to lessen noise during use.
 16. The bicycle frame of claim 14, further comprising: a first support strut extending from the bottom bracket to the forward end of the arced component; a second support strut extending from the bottom bracket to a rear end of the arced component; and a shock damping pad mounted to the first support strut and positioned between the seat tube and the first support strut.
 17. The bicycle frame of claim 16, further comprising: a bracket mounted between the first support strut and the second support strut, wherein the bracket is configured to support a front derailleur.
 18. A bicycle, comprising: a frame including a head tube, a top tube extending rearward from the head tube, an arced component having a forward end coupled to the top tube and a lower curved surface having a plurality of holes, and a bottom bracket positioned below the arced component; a seat tube including a pivot attachment at a lower end of the seat tube, wherein the pivot attachment is coupled to the bottom bracket so that the frame is pivotable relative to the seat tube about the bottom bracket resulting in a plurality of seat tube positions between a fully forward position and a fully back position; a locking mechanism configured to selectively lock the seat tube to the arced component at one of the seat tube positions, wherein the locking mechanism includes a lock ring with a plurality of lock pins and a first spring that pushes the lock ring towards the arced component, wherein the lock ring and the first spring surround the seat tube, and wherein the lock ring is movable between a locked position in which the lock pins are inserted into the holes and an unlocked position in which the lock pins are removed from the holes and the frame is free to pivot about the bottom bracket; a second spring coupled between the head tube and the seat tube to pull the seat tube towards the fully forward position, wherein the second spring is located within the top tube a saddle movably coupled to the seat tube so that the saddle is adjustable up and down relative to the seat tube; a front wheel coupled to the frame; a rear wheel coupled to the frame; and a handlebar coupled to the head tube; wherein with the lock ring in the unlocked position, the seat tube remains stationary and the frame pivots to follow the terrain on which the bicycle is being ridden.
 19. The bicycle of claim 18, wherein the seat tube is fixed with respect to gravity so that with the bicycle going up a hill and the locking ring in the unlocked position, the frame pivots so that the seat tube is moved toward the fully forward position, and with the bicycle going down a hill and the locking ring in the unlocked position, the frame pivots so that the seat tube is moved toward the fully back position.
 20. The bicycle of claim 18, further comprising an eccentric bushing though which an axle of the rear wheel passes, the eccentric bushing allowing alignment of the rear wheel relative to the arced component. 